Subodh Varma, TNN Nov 16, 2012, 02.49PM IST
NEW DELHI: The record for the most distant galaxy from Earth has been broken just two months after it was set. What appeared as a tiny blob to Nasa scientists turned out to be a small infant galaxy 13.3 billion light years away, Nasa said in a statement yesterday. Since the Universe itself is 13.7 billion years old, this means that the newly discovered galaxy was just 420 million years old when the light that scientists saw, left it. So, it also becomes the oldest known galaxy. Currently, it is known as MACS0647-JD.
The previous record was set in September this year when the same team discovered a galaxy 13.2 billion light years away. It was 490 million old.
Scientists are now able to discover these uber-distant objects by combining the power of Nasa's Hubble and Spitzer space telescopes and one of nature's own natural "zoom lenses" in space. Light from very distant objects gets magnified by the gravity of massive galaxies that happen to be in its way. This effect is called "gravitational lensing".
This find is the latest discovery from a program called Cluster Lensing And Supernova Survey with Hubble (CLASH), an international group led by Marc Postman of the Space Telescope Science Institute in Baltimore.
Along the way, 8 billion years into its journey, light from MACS0647-JD took a detour along multiple paths around the massive galaxy cluster MACS J0647+7015. Without the cluster's magnification powers, astronomers would not have seen this remote galaxy. Because of gravitational lensing, the CLASH research team was able to observe three magnified images of MACS0647-JD with the Hubble telescope.
"This cluster does what no man-made telescope can do," said Postman. "Without the magnification, it would require a Herculean effort to observe this galaxy."
The newly discovered most distant galaxy is so small it may be in the first steps of forming a larger galaxy, Nasa said. Analysis shows the galaxy is less than 600 light-years wide. Based on observations of somewhat closer galaxies, astronomers estimate that a typical galaxy of a similar age should be about 2,000 light-years wide. For comparison, the Large Magellanic Cloud, a dwarf galaxy companion to the Milky Way, is 14,000 light-years wide. Our Milky Way is 150,000 light-years across.
"This object may be one of many building blocks of a galaxy," said the study's lead author, Dan Coe of the Space Telescope Science Institute. "Over the next 13 billion years, it may have dozens, hundreds or even thousands of merging events with other galaxies and galaxy fragments."
Coe and his collaborators spent months systematically ruling out these other alternative explanations for the object's identity, including red stars, brown dwarfs and red (old or dusty) galaxies at intermediate distances from Earth. They concluded that a very distant galaxy was the correct explanation.
The new galaxy may be too far away for any current telescope to confirm the distance based on spectroscopy, which spreads out an object's light into thousands of colors, Nasa said. Nevertheless, Coe is confident the fledgling galaxy is the new distance champion based on its unique colors and the research team's extensive analysis.
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